Electrochromism in sputter deposited nickel-containing tungsten oxide films

Thin films of NixW1-x oxide were prepared by reactive DC magnetron co-sputtering and were investigated by optical and electrochemical measurements. Electrochromism was found only for 0 < x < 0.3 but not for 0.3 < x < 0.6, though films with x similar to 0.4 could still sustain reversible charge insertion. The coloration efficiency was largest for 0.10 < x <0.15. The charge capacity of the NixW1-x oxide films decreased upon increasing the value of x as a consequence of a decreasing ion diffusion coefficient leading to slower kinetics. (C) 2012 Elsevier B.V. All rights reserved.